Antistatic photographic film



Patented May 13, 1947 UNITED STATES PATENT OFFICE ANTISTATIC PHOTGRAPHEC FLM Application December 14, 1945, Serial No. 635,047

12 Claims.

This invention relates to photographic film and more particularly to nlm having anti-static coatings.

Considerable difculty has been encountered in the manufacture and use of photographic film due to the accumulation of electrical charges on the film. These electrical charges, which are known as static, develop when photo-graphic ilm is handled during processing as, for example, when lm sheets are separated from each other or when motion picture film is passed through a projector. The more serious diiiiculty is the accumulation of static in the application of the various coatings in the manufacturing process of the photographic film and in the passage of manufactured film through the camera. Manifestations of these charges are glow discharges which after development of the exposed lm show up as black streaks or lines, or as irregular fogged patterns in the emulsion layer. Attempts have been made to overcome static in lms by the application of substances which are electrolytes or possess hygroscopic properties. The function of these substances is to impart conductivity to the film and thus dissipate the electrical charges before their accumulation leads to local discharges. Many of these substances are incompatible with the materials which form one or more layers of the photographic iilm and introduce new manufacturing diiculties.

An object of the present invention is to provide means for eliminating static charges on a photographic lm.

A further object is to provide means for reducing static charges in a photographic lm base during coating of the sensitive silver-halide emulsion.

A still further object is to provide means for reducing static charges in a photographic lm during passage through a camera or printer.

Further objects Will appear hereinafter.

` These objects are accomplished by the present invention by incorporating, in layers of the film or on the surface of the film, a di-alkyl ester of phosphoric acid of the following general formula:

wherein one of the Rs is a short chain alkyl group ranging from 1 to 5 carbon atoms, e. g., methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl, isoamyl, and the like, and the other R represents an alkyl group ranging from 5 to 18 carbon atoms, e. g., butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, heptadecyl, octadecyl, and the like.

Di-alkyl esters of phosphoric acid represented by the above general formula are commercially available, and the method of their preparation need not be described herein.

As suitable examples of cli-alkyl esters of phosphoric acid, the following may be mentioned:

Methyl amyl hydrogen phosphate thyl amyl hydrogen phosphate Propyl octyl hydrogen phosphate Butyl nonyl hydrogen phosphate Amyl decyl hydrogen phosphate Methyl dodecyl hydrogen phosphate Ethyl dodecyl hydrogen phosphate Ethyl tetradecyl hydrogen phosphate Methyl heXadecyl hydrogen phosphate Methyl octadecyl hydrogen phosphate Ethyl octadecyl hydrogen phosphate These esters may be applied to the film in various ways to eliminate static. As for example, they may be applied as a constituent of a sub-layer or as a coating over a sub-layer; to the finished film either on the obverse surface, reverse surface or to the light-sensitive emulsion; or to either surface of the exposed and processed film. The various modes of applying these esters will now be described with reference to the accompanying drawing.

in the accompanying drawing Figs. l to 6, inclusive, represent sectional views of a film provided with anti-static layers in accordance with the present invention.

As shown in Fig. 1 a film base of transparent material such as a cellulose organic ester, for eX- ample, cellulose acetate, cellulose formate, cellulost proprionate, cellulose butyrate, cellulose acetate-propionate, cellulose acetate-butyrate, and the like, or cellulose nitrate, or film-forming polymers, such as polyvinyl chloride, copolymers of vinyl chloride-vinyl acetate, copolymers of vinyl chloride-vinylidene chloride, polyamides, superpolymers and the like, is coated with a thin gelatin sub-layer 2 to which has been added one of the cli-alkyl esters of phosphoric acid referred to above. The light-sensitive emulsion layer 3 is coated directly over this gelatin sub-layer.

In the modification shown in Fig. 2, the base l is coated with the usual gelatin sub-layer 4 and directly over this layer is coated a solution of one of said di-alkyl esters of phosphoric acid 5. The light-sensitive emulsion layer 3 is coated directly over the layer 5,

In Fig. 3 the support l is coated with the usual gelatin sub-layer 4 and the light-sensitive emulsion layer The anti-static layer 5 consisting of a solution of such di-alkyl ester of phosphoric acid is coated over the light-sensitive emulsion layer 3.

The anti-static layer may be applied to a film base I opposite to that bearing the usual gelatin sub-layer` 4 and light-sensitive emulsion layer 3 60 as shown in Fig. 4.

In Fig. 5 the support l is coated With the usual gelatin sub-layer Over this sub-layer is coated a light-sensitive emulsion layer 6 containing such di-alkyl ester of phosphoric acid.

In Fig. 6 the base l is coated with the usual gelatin sub-layer 4 and light-sensitive emulsion layer 3. The anti-halation layer 'l containing one of said di-alkyl esters of phosphoric acid is coated on the opposite side of the lm base I.

The cli-alkyl esters of phosphoric acid may be applied to the iilm either in a solvent or n a non-solvent for the nlm base. Where the ester is applied in admixture with a light-sensitive emulsion, or beneath the sensitive layer or over the sensitive layer, it is appiied either in an aqueous solution or some other suitable solvent which does not adversely eiect the light-sensitive emulsion, such as for example, methyl or ethyl alcohol and the like. In employing the di-alkyl esters of phos nic acid as a backvvash, they may be applied to the nlm casein a solvent such as methanol, acetone or a mixture thereof, or in a 1.5% solution of gelatin, or an alkali soluble resin prepared according to United States Patent 2,089,764.

The following specific examples illustrate several of the various methods oi applying these dialkyl esters or" "ifiosphoric acid anti-static coatings, and it l be understood that these eX- amples merelv represent the preferred embodiments and are not to he considered as limitative.

E'Lrample I 20.0 cc. of a 5% solution or methyl dodecyl hydrogen phosphate in methanol are dispersed in 5o cc. of 1.5% gelatin and applied as top layer upon a light-sensitive silver-halide emulsion.

,Erampe II 5.0 of ethyl tetrad cfl 'iydrogen phosphat@ are difisol sisting of meth..

de cy ellosh yd g er.

about 59% are dispersed c 'e onsi ng of 39% methanol and 70% acetone. 'This dispersion is applied as a baciA .rsh upon a cellulose nitrate hase.

10S cc. or" a l drogen p solution of methyl dodecyl hycsphate in methanol are mixed with 1G kil ci a silver-halide emulsi n (containing -i-; slveiwhalide) coated over a gelatin-subhed cellulose acetate base.

l@ cc o 1C or dodecyl hyn drogen al hat .noi are dispersed in disp -n Y liglitsensit-ve The above spe as merely iilust ol t'ie invention, and :not in any sense f It will he o'ovious to anyone skilled in tl e art that Aany inodiications such as substituting equivalent material and varying the proportions of materials used are o he Within the spirit and scope of the invention as deined in the appended claims.

I claim:

l. A photographic element comprising a support carrying a photographic emulsion layer and an anti-static layer comprising a di-alkyl ester of phosphoric acid corresponding to the following general formula:

wherein one of the Rs is a short chain alkyl group ranging from 1 to 5 carbon atoms, and the other E represents an alkyl group ranging from 5 to 18 carbon atoms.

2. A photographic element comprising a support carrying a photographic emulsion layer and an anti-static layer comprising methyl dodecyl hydrogen phosphate.

3. A photographic element comprising a support carrying a photographic emulsion layer and an anti-static layer comprising ethyl tetradecyl hydrogen phosphate.

f1. A phctcgr phic element comprising a supplente-graphic emulsion layer and ayer comprising ethyl octadecyl hydrogen phosphate.

5. A photographic element comprising a support ca rying a photographic emulsion layer and between said support and said emulsion layer,

an anti-static layer comprising a dialkyl ester oi phosphoric acid corresponding to the following general formula:

wherein one of the Rs is a short chain alkyl group ranging from 1 to 5 carbon atoms and the other R represents an alkyl group ranging from to 18 carbon atoms.

6. A photographic element comprising a support carrying a photographic emulsion layer and, on the opposite side of said support, an antistatic layer comp sing a dialkyl ester of phosphoric acid corresponding to the following general lformula:

wherein one of the Rs is a. short chain alkyl group ranging from l to 5 oaroon atoms and the other R represents an alkyl group ranging from 5 lto 18 carbon atoms.

7. A photographic element according to claim 5 in which the anti-static layer comprises methyl dodecyl hydrogen phosphate.

.ic element according to claim which the enti-static layer comprises ethyl decyl hydrogen phosphate. 9. A photographic element according to claim which the anti-static layer comprises ethyl decyl hydrogen phosphate.

i photographic element according to claim which the anti-static layer comprises methyl ecyi hydrogen phosphate. l. A photogr 'c :c element according to claim l2. A photographic element according to claim 6 in which the anti-static layer Ycomprises ethyl octadecyl hydrogen phosphate.

FRITZ W. H. MUELLER. 

